Terms and References used in the Locust Bulletin

Adult

A fully winged, mature locust capable of developing eggs and migrating.

Aerial control

APLC or State control by aircraft fitted with Micronair rotary cage atomisers - spraying insecticide using ultra low volume (ULV) equipment.

Aerial survey

During periods when locust activity has increased fixed wing aircraft may be used to find bands and helicopters to find swarms. The aircraft are used to enable the maximum area to be surveyed as quickly as possible.

Band

Gregariously behaving group of nymphs at a density greater than 80 locust nymphs per square metre. Bands have well defined fronts and nymphs "march" in the same general direction.

Breeding

Mating, reproducing

Concentration

0.5-3 locusts per square metre on the ground and not flying as a gregarious group.

Day flight

Short distance (up to 50 km/day) daytime migratory movement of gregariously behaving locusts, generally at low altitude (0 – 300 m), resulting in redistribution of a population. 

Development

General term covering all stages of the locust life cycle from egg to adult.

Diapausing
egg

An over-wintering egg that does not develop for several months. Diapause ends by mid June and development resumes as soon as conditions are favourable.

District

Forecasting areas referred to in the Bulletin (see map).

Early instar

First and second instar locusts

Egg bed

An area containing more than 10 egg pods per square metre.

Emigrants

Locusts leaving an area by migration.

Fledgling

Newly moulted, soft-bodied adult incapable of sustained flight. This stage lasts approximately 5 days. 

Gravid

Females with mature eggs of 4-5 mm length.

Ground control

Locust control from ground based vehicles employed by State Authorities, Rural Lands Protection Boards (NSW) and landholders. The insecticide formulations used are generally emulsifiable concentrates or wettable powders. The APLC does not carry out ground control.

Immigrants

Locusts which fly into an area.

Instar

Stage of nymphal development of an insect. Each instar is separated by a moult. Australian plague and migratory locusts have five nymphal instars while the spur-throated locust has 6-8 instars.

Late instar

Fourth and fifth instars.

Females depositing eggs into the ground in egg pods containing up to 50 eggs for Australian plague and migratory locusts and 120 for spur-throated locusts.

Light trap

Apparatus comprising a light source and water trap to which locusts are attracted at night. An increase in the catch may indicate migration.

Mid instar

Third instar locusts

Migration

Nocturnal, wind-assisted flight of locusts usually at higher altitudes (up to 1200 m), resulting in population displacement up to several hundred kilometres overnight.

Nymph

Immature locust without wings (though wing buds may be visible) and is therefore unable to fly. This stage in the locust life cycle follows hatching, lasts approximately four weeks and is often referred to as the hopper stage.

Over-wintering eggs

An egg in an arrested state of development (diapause or quiescence).

Over-wintering 

nymphs

Over-wintering nymphs resulting from an autumn laying generally develop to third instar and persist through winter in that stage. Development resumes in spring. 

Over-wintering adults

Over-wintering locusts that become adult in late autumn but do not mature and develop eggs until early spring.

Quiescent egg

An egg in which development has been arrested by the onset of dry conditions and which will resume development when sufficient rain falls.

Region

Grouping of forecast districts (see map) or commonly understood regional terms.

Reports

Information from APLC staff is referred to using the terms 'seen', 'found' and 'observed' and that from other sources as 'reported'. 

Sub-band

Locust nymphs at a density between 31 and 80 individuals per square metre. Sub-bands have no well-defined front and little tendency to "march" together.

Surveys

Generally these are carried out along roads and tracks with stops at regular (approx. 10 km) intervals. At each stop the numbers and stage of development of each locust species is recorded for a 250m foot traverse. The type and condition of the vegetation are also recorded.

Swarm

Gregariously behaving group of adult locusts flying together as a unit at a density greater than four individuals/m².

Target

An area of band or swarm density locusts at least 1km² in size.

Test drilling

Female locusts bore into the ground with their abdomens to test the soil but do not lay eggs